1. Field of the Invention
This invention relates generally to window treatments, and more particularly, to a safety clutch device used with tube lifts in pleated shades, venetian blinds and other window treatments.
2. Description of the Prior Art
Window treatments such as shade assemblies and venetian blinds typically have window covering material or blind slats extending between a headrail and bottomrail and two or more lift cords connected to the bottomrail. Within the headrail is some type of cord locking device. Typically, two or more lift cords are connected at one end to the bottomrail and extend up through the window covering material or blind slats into the headrail. The lift cords then pass through a cord locking device and out of the headrail such that an opposite end of the lift cords is accessible to an operator. This type of blind can be seen in prior art FIG. 1.
Another type of blind has a tube lift in which the lift cords are wound around a tube within the headrail. An example of this type is shown in U.S. Pat. No. 5,184,660 issued on Feb. 9, 1993 to Jelic. By way of brief explanation, an endless looped pull cord is used to rotate a lift tube around which the window blind lift cords are wound and unwound in order to raise and lower the window blind. Usually a clutch is provided at one end of the tube lift. An endless cord is looped around a spool portion of the clutch to operate the lift system.
The lift cords of the window treatment present an attractive danger to infants or children who may play with the lift cords. There have been several instances in which children and infants have become entangled in the cords and accidentally hanged. This is more likely to occur when the lift cord is an endless loop as in FIG. 1 or the lift cords are tied together. Consequently, there has been a need for a lift system for window blinds that do not have a cord loop or tied lift cords.
In the past, attempts to reduce the danger associated with these lift cords have focused on moving the lift cords out of the accessible range of infants such as by tying or clipping the cords to shorten them or otherwise moving the lift cords away from floor level and away from the infants reach. Moving the cords out of the way after use is troublesome, and the operator must remember to move the cords after each use. Other attempts have focused on a detachable connection of the lift cords ends such as is disclosed in U.S. Pat. No. 4,909,298 to Langhart et al. Detachable lift cords require a certain level of force to detach. Moreover, tests of the commercially available embodiment of the Langhart patent have shown that this product failed to detach in simulated entanglements. Furthermore, the clutches currently in use for tube lift systems are designed to use a cord loop, not detachable lift cords. And although window treatments are designed to be aesthetically pleasing, none of the attempts of the prior art to reduce the dangers associated with lift cords are particularly aesthetically pleasing. Thus, there is a need in the industry to reduce the danger associated with lift cords in an efficient yet aesthetically pleasing manner.
It is therefore an object of the present invention to provide a window treatment having a lift mechanism which does not present a danger to infants or children.